Lake Arnen, reservoir in Gsteig bei Gstaad in the Bernese Alps, Switzerland

Lake Arnen (Arnesee) is a reservoir at 1,541 m above sea level near Gsteig in the Bernese canton, held by a 17-metre-high earth-fill dam on the Tschärzisbach. Its surface covers 45 hectares, it stretches 1.5 km and holds 11.9 million m³ of water. The 140-metre-long dam crest was completed in 1942.

The Arnensee was created as a reservoir when a 17-metre earth-fill dam, completed in 1942, impounded the Tschärzisbach stream. The dam, with a 140-metre-long crest, holds back 11.9 million m³ of water. The stored water feeds a chain of three turbines operated by Romande Energie in the canton of Vaud: Les Diablerets (5 MW, 380 m head), Pont de la Tine (3.5 MW, 350 m) and Les Farettes (5.5 MW, 350 m, 20 km away).

The lake lies in the German-speaking municipality of Gsteig, but its official name is Arnesee and its French name Lac d'Arnon, a sign of the language border running through these Alps. A forest nature trail circles the reservoir with panels on the plants and animals of the surrounding woods, and a picnic and barbecue area sits at the southern tip.

A toll road runs from Feutersoey up to the dam, where a restaurant stands. The dam crest is 140 metres long and the circular trail around the reservoir is a forest nature trail with panels on local plants and animals. A barbecue area lies at the southern tip of the lake.

The dam that holds the lake is an earth-fill embankment 17 metres high with a 140-metre-long crest. Water from the Tschärzisbach is carried through three turbines in canton Vaud: at Les Diablerets (5 MW, 380 m drop), Pont de la Tine (3.5 MW, 350 m drop) and Les Farettes near Aigle (5.5 MW, 350 m drop, 20 km away).